Kernel Dashboard is missing edges without a path to a syscall

The way the dashboard is generated is that we only show it in the list if there is a known path to a syscall (because we do an [inner join](https://github.com/google/security-research/blob/bf0d68f3ce617bdfe6b01ce4c205b56116884b29/analysis/kernel/dashboard/frontend/db/sql/codeql_data-6.1.db/prolog.sql#L91))

However, there are interesting paths from what originally are things like function pointers, which would be good to show too.

We can do this by doing a UNION SELECT with edges_with_functions rather than just one with edges_with_functions_per_syscall here: https://github.com/google/security-research/blob/master/analysis/kernel/dashboard/frontend/db/sql/codeql_data-6.1.db/query-Paths_getParentEdgesByFileLine.sql

An example of a function with "parents" that don't come from direct callgraph from a syscall is [blkcg_unpin_online](https://storage.googleapis.com/kernelctf-dash/processed/v6.1.111/index.html#block/blk-cgroup.c:1108:1118
) so it shows up as an empty parent